If you’re experiencing swelling in just one knee, there could be several possible causes. Here are some of the most common reasons and when to seek medical attention:
Possible Causes of One Swollen Knee:
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Trauma or Injury
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Sprains, strains, or ligament tears (e.g., ACL injury)
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Fractures or meniscus tears
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Bursitis (inflammation of the fluid-filled sacs around the knee)
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Infections (Septic Arthritis)
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Bacterial or viral infections can cause sudden, painful swelling, often with fever.
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Requires immediate medical treatment to prevent joint damage.
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Gout or Pseudogout
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Gout (uric acid crystals) causes sudden, severe pain, redness, and swelling.
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Pseudogout (calcium crystals) has similar symptoms but is less common.
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Osteoarthritis (Wear-and-Tear Arthritis)
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Typically affects one knee more than the other, especially in older adults.
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May cause stiffness, pain, and swelling after activity.
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Rheumatoid Arthritis (Autoimmune Condition)
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Usually affects both knees, but early stages may start on one side.
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Baker’s Cyst (Popliteal Cyst)
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A fluid-filled sac behind the knee that can cause swelling and stiffness.
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Blood Clot (Deep Vein Thrombosis – DVT)
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If swelling is accompanied by warmth, redness, and calf pain, seek emergency care (risk of pulmonary embolism).
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When to See a Doctor:
✔ Severe pain or inability to bear weight
✔ Fever, redness, or warmth (signs of infection)
✔ Sudden swelling after an injury
✔ Swelling lasting more than 3 days without improvement
At-Home Care (Mild Cases):
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R.I.C.E. Method: Rest, Ice, Compression, Elevation
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Over-the-counter pain relievers (NSAIDs like ibuprofen, if no contraindications)
If swelling persists or worsens, consult a healthcare provider for proper diagnosis (possibly X-rays, ultrasound, or fluid aspiration).
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